KISSIMMEE, Fla. — Twelve-year-old Cecily Vammino’s eyebrows shot up as she closed her lips around the veggie pie. It was a subtle mélange of carrots, potatoes, and zucchini, surrounded by a vaguely sweet crust, and it was not working for her.

Cecily’s jaw carefully dispatched the invader while her left hand slid the remaining threat to a place where it could not harm her.

“Uh-uh,” she said, shaking her head.

Like every other meal Cecily would be sharing with 19 other children and their parents this month, this one was freshly cooked and served by the crack staff of kitchen professionals who were working under strict orders: Give the kids anything they want, as long as it’s all organic, and free of gluten, dairy, salt, and processed sugar.

It was a grand medical — and, in ways, social — experiment. The children are all living with a rare kidney disorder called focal segmental glomerulosclerosis, or FSGS, in which their kidneys leak proteins into the bloodstream. The disease strikes 5,000 people in the United States each year, and for a subset of pediatric patients, like most of those here, treatments like steroids and immunosuppresants don’t help. They face painful symptoms and, eventually, the prospect of kidney failure.

For decades, FSGS has represented a stubborn medical mystery, but in recent years researchers have unearthed clues that have led them to ask a simple question. In an age when seemingly every ailment is treated with a pill, could a change in diet essentially force this disease into remission and, possibly, save these children’s lives?

“It would be huge,” said Dr. Leonardo Riella, the black-bearded nephrologist who is leading the research team here. “We’re hopeful, but we will see.”

To get to the answer, though, Riella and his colleagues had to first design a research trial that could control the children’s diet long enough to observe possible effects, in a place where medical and scientific protocols could be followed — and, importantly, in an environment that might tempt families to sacrifice a month of their lives in the name of science.

Two ideas came to mind: camp and Disney.

Since it would be difficult to find an established camp in Orlando that could accommodate such dietary restrictions for a large group, Riella and his team at Brigham and Women’s Hospital in Boston created a camp-like environment at a water park resort here.

For every time Cecily and her friends confronted veggie pies (and whipped avocado desserts), there were considerable perks: a romp at the water park, movies in a huge in-home theater, a private performance from former Ringling Bros. acrobats, and trips to Disney.

It was all experienced from the confines of luxurious houses with backyard pools. It was all for free. And it was all in the name of science.

Cecily Vammino (center) and other campers get ready to play games at the water park in Kissimmee.

Dr. Leonardo Riella examines Faulkner on lab day during the camp.

Riella’s clinical trial has its roots in a bit of research conducted in the early 1970s, the results of which were published in the Lancet. That small pilot study suggested that a subset of patients with nephrotic syndrome, a condition related to FSGS, improved while on dairy-restricted diets. Despite multiple similar case reports that followed, most of the field focused on drug treatments instead of dietary changes.

“But there’s always been chatter about this,” said Lauren Lee, director of research and engagement for NephCure Kidney International, a Pennsylvania-based advocacy group for people with FSGS and other protein-leaking kidney disorders. (NephCure helped recruit patients for the trial.)

Then, three years ago, the parents of a 1-year-old girl in Brazil with nephrotic syndrome reached out to Riella. The girl’s condition had failed to improve with conventional treatments. Her parents had read that modified diets had helped others, and wondered if their daughter’s disease might be related to food sensitivity. They asked a doctor in Brazil to guide her through a new diet.

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Within two weeks, the girl’s kidneys all but stopped leaking protein, and she effectively went into remission. Her parents were ecstatic, but they also wanted the medical community to better understand the mechanisms of this intervention, in hopes that doctors would embrace it as a treatment.

They were prepared to anonymously fund a research trial, but they wanted it done quickly.

As in this summer.

“I thought, ‘No way could we make it happen,’” said Riella, back in one of the three houses the research team rented for the trial — one of which serves as the cafeteria and medical-team headquarters.

Riella, who is associate director of the Brigham’s kidney transplant program, has published widely on issues related to nephrotic disorders and immune-related topics, and is currently investigating a drug that could increase the success of kidney transplants.

For the Orlando-area study, at least, there would be no need for lengthy Food and Drug Administration approvals because no drug was involved. But he still needed to design the protocol, have it approved by his hospital’s review board, and set up the operation 1,300 miles away from his office.

And then there was the small matter of recruiting 20 families to participate.

“We thought, could we make a fun environment for them?”

Aside from attracting families who would appreciate weekly theme park visits and almost-daily water park trips, Riella suspected the camp-like environment would appeal to a group of people who rarely meet others with their condition. It would also provide an environment for educational programming, like health lectures, cooking classes, and shopping tips, to help them eat a more kidney-friendly diet.

The parents of the girl in Brazil agreed to foot the bill (while insisting on anonymity). The next step was to find participants.

The medical team reached out to colleagues worldwide and attracted families from Belgium, Peru, Mexico, Brazil, and the U.S. While locking down commitments from 20 families, they designed a testing protocol that would enable them to ship samples overnight to their Boston lab for analysis.

The participants will be encouraged to revert to their normal diets when they’re home, and they’ll be tested again one month later to compare results.

Other researchers are watching the trial with interest. “There is no doubt that the scientific question is important and the evaluation of the diet and its impact in a strictly controlled setting is ideal,” said Dr. Bradley Warady, a research physician who treats pediatric nephrology patients at Children’s Mercy Kansas City. “Whether or not a one-month evaluation is sufficient remains to be seen.”

Former circus performer Viktoria Zsilak entertains the campers.

Taylor Faulkner, 21, slumped on a lounge chair at the poolside on a muggy Wednesday afternoon. “I think we’re all a little tired still from Monday,” she said.

Monday was the group’s second theme park side trip, and the kids didn’t get to bed until nearly midnight. Children with FSGS often tire easily, and the group was still adjusting to their new diet, as well as new beds, noisy homes, and 8 a.m. breakfasts.

Faulker, who is a musical-theater major at Northwest Florida State College, is the oldest participant by several years, and is the de facto big sister of the crew. Children gravitate toward her and she indulges them with applause, bright smiles, and laughter. She wears her hair in broad curls and a “Despicable Me” bandage over the spot on her arm where her blood was drawn.

Faulkner was 18 when she first noticed strange swelling in her ankles and a metallic taste in her mouth. The swelling is a telltale sign of nephrotic syndrome; swollen faces appear in the morning, and then, after a day of walking or sitting, the fluid settles in the ankles.

Often patients need hospitalization and a cocktail of drugs that draws fluid from the body, while replacing the lost protein. Patients also frequently need drugs to reduce the high blood pressure that accompanies the condition — usually steroids, which are commonly prescribed to limit protein leaking.

The side effects from the medications, Faulkner says, are worse than the symptoms from the disease. Her current treatment, tacrolimus, is usually prescribed to people who undergo organ transplants, and it suppresses the immune system so she can’t be around people who are ill.

Like most others in this study, such medications can generally control her symptoms, but because they don’t control the underlying disease, her kidneys will eventually scar, putting her on course for dialysis or a transplant.

“That’s something I worry about, a bit,” she said.

But she and others in the group had heard that a couple of the kids had had their urine tested for protein leakage by their private doctors, and the diet seemed to be having an effect already.

“We know something’s working,” she said. She listed five different medications she’s currently taking, and mused about the prospect of one day trashing them. “That would be insane.”

Campers practice balancing an ostrich feather on their finger after watching a circus performance.

Feeling dizzy, Vammino covers her eyes after phlebotomist Shauna Elliott removes the collection tube and needle from her arm during lab day.

On the morning before exam day, Jodie Urias and four other veteran circus performers led the campers through 15-minute workshops in circus arts, including juggling, hula hooping, and tumbling.

True to day-camp form, most of the kids resisted switching from their favorite activities, but were quickly wrangled by the circus specialists, who played the part of sweetly stern camp counselors.

After an evening of movies and cellphone scrolling, they rested for the next morning’s medical regimen. The children delivered urine and frozen stool samples to the medical team, stood for pictures (to track swelling), then underwent exams by Riella and had their blood drawn.

Some of the smaller children in particular clung to their mothers and wailed in fear of the phlebotomist, but most have endured so many needles that they barely flinched when the moment came. Cecily, for one, said she’d been stuck with needles plenty in her life.

Despite some occasional struggles with the food, she said the camp experience has been positive — mostly because she made friends “after about five minutes.”

Her mother, Dena, has been trying to continue her job duties as a software consultant while accompanying Cecily. She said Cecily has been lucky with her disease, in that her outward symptoms have been all-but-invisible, though her kidneys are as burdened as many others.

Faulkner, 21, sports a Minions bandage after having her blood drawn on lab day.

Indeed, one of the benefits of the trial, Dena said, was that Cecily can better understand the implications of the disease. “It really hits home here,” she said. “And I’ve learned so much, too, from the workshops and just getting to know everyone else.”

Visiting Disney with severe dietary restrictions, though, can be tricky.

“You see other kids walking by with the Mickey Mouse ice cream, and our kids are like following them, hoping a piece breaks off so they can eat it,” Dena said, laughing. “So yeah, it can be tough in the parks. I won’t lie.”